This invention relates in general to controllers for electric motors and in particular to IC controller chips for brushless dc motors.
The rising popularity of brushless dc motors has brought a need for small, low-cost controllers. A typical motor controller includes four elements: rotor position sensors which provide signals indicating the position of the motor's rotor with respect to its stator windings; commutation logic which generates commutation commands in response to the rotor position signals; a power supply; and an inverter containing power transistors, either bipolar or field-effect, which commutate power to the motor' stator windings in response to the commutation commands.
The commutation logic can be fabricated on a single integrated circuit (IC) chip, and the power supply and inverter are implemented with discrete analog components. The resulting controller is a marriage of an analog element (the inverter), a digital element (the IC chip) and a power supply.